Superior oblique myokymia is a microtremor of the eye that causes monocular
torsional oscillopsia. A modified Harada-Ito procedure was used to treat a
case of the disease in a 20-year-old woman. The authors used video-image a
nalysis pre- and postoperatively to evaluate the effect of the surgery on a
bnormal torsional eye movements. This analysis revealed that before surgery
, the abnormal torsional movement had a very regular cycle (duration or att
ack, 8.0 +/- 0.5 s; time interval between attacks, 18.7 + /- 3.2 s; n = 9).
After the surgery, amplitude of the abnormal torsional eye movement was re
duced, and the oscillopsia had subjectively improved, although the movement
cycle remained unchanged. The authors ' video-image analysis, which used i
ris striation, proved to be a useful method for clinical measurement of tor
sional eye movements.